The results are consistent with other estimates, but this is the first time scientists have used actual observations from this far back in time rather than relying on model-generated estimates. “We have observation-based estimates that is new and super important,” emphasized Kristian Kjellerup Kjeldsen, the lead author of the study at the Natural History Museum of Denmark.

Even the Intergovernmental Panel on Climate Change was missing these crucial data about Greenland’s ice melt in its 2013 assessments of sea-level rise, which excluded the contribution of the ice sheets. The gap existed because of the lack of direct observations of Greenland, according to scientists.

One of the limitations of the work, Kjeldsen pointed out, was comparing rates of ice loss in time periods of different lengths. Their estimations show an average annual ice loss of about 75 gigatons for the first two phases—an 80-year-long period and a 20-year one. The most recent data showed that an average of 186 gigatons of ice was lost during 2003-10, which is only a seven-year period.

Last century 75 Gton a year, then last decade up to 186 a year, more than double.This decade, looking for data.... 2012 report

For the first time and for each region, the researchers could determine with unprecedented precision which percentage melting, iceberg calving and fluctuations in rainfall have on the current mass loss. "Such an increase in mass loss in the northwest after 2005 is partly due to heavy snowfall in the years before", says GFZ scientist Ingo Sasgen, head of the study. "The previous mass gain was reduced in subsequent years. Similarly in eastern Greenland: In the years 2008 and 2009 there was even a mass increase". As the researchers were able to show, this was not due to decreased glacier velocities, but because of two winters with very heavy snowfall. Meanwhile, the loss of ice mass continues here. For all studied regions the melting and calving periods between 2002 and 2011 are extraordinarily high compared to those of the last five decades.

Less than a year after the first research flight kicked off NASA's Oceans Melting Greenland campaign, data from the new program are providing a dramatic increase in knowledge of how Greenland's ice sheet is melting from below. Two new research papers in the journal Oceanography, including one by UCI Earth system scientist Mathieu Morlighem, use OMG observations to document how meltwater and ocean currents are interacting along Greenland's west coast and to improve seafloor maps used to predict future melting and sea level rise.

5 year program started in 2017 so this is the best and most recent info on the melting GIS.

The OMG data have enough detail that researchers are beginning to pinpoint the ice-loss risk for individual glaciers along the coast, according to principal investigator Josh Willis of JPL. "Without OMG, we wouldn't be able to conclude that Upernavik Glacier is vulnerable to ocean warming, whereas Cornell Glacier is less vulnerable," he said.

Darn, we might have to wait a bit for the results, no mention of any Gton/year either:

OMG is a five-year campaign to study the glaciers and ocean along Greenland's 27,000-mile coastline. Its goal is to find out where and how fast seawater is melting the glacial ice. Most of the coastline and seafloor around the ice sheet had never been surveyed, so the 2016 flights expanded scientists' knowledge of Greenland significantly. Future years of data collection will reveal the rate of change around the island.

The water circulating close around the Greenland Ice Sheet is like a cold river floating atop a warm, salty ocean. The top 600 feet (200 meters) of colder water is relatively fresh and comes from the Arctic. Below that is saltwater that comes from the south, 6 to 8 degrees Fahrenheit (3 to 4 degrees Celsius) warmer than the fresher water above. The layers don't mix much because freshwater weighs less than saltwater, so it stays afloat.If a glacier reaches the ocean where the seafloor is shallow, the ice interacts with frigid freshwater and melts slowly. Conversely, if the seafloor in front of a glacier is deep, the ice spills into the warm subsurface layer of saltwater and may melt relatively rapidly. Satellite remote sensing can't see below the surface to discern the depth of the seafloor or study the layers of water. OMG makes these measurements with shipboard and airborne instrume

Report from this year, 287 Gton, almost a doubling from the 2003/2010 period. Exponential, abrupt change happening.

“We find that 2003–2010 mass loss not only more than doubled relative to the 1983–2003 period, but also relative to the net mass loss rate throughout the twentieth century,” the study notes. It states that mass loss in this most recent period, ending in 2010, was 186 gigatons per year on average, though other estimates have put that number even higher for the most recent years. NASA currently states that Greenland is losing 287 billion tons of ice per year.

Ice loss from Greenland today occurs through two key mechanisms — melting on the surface of the ice sheet followed by runoff into the ocean, and large calving events at marine based glaciers, which are followed by more flow of ice outward from behind them.The latter process can be quite dramatic — capable of triggering huge earthquakes as gigaton-sized icebergs detach, roll in the water, and crash into glaciers behind them.

No worries:

Since the end of the study period in 2010, mass loss has only continued, with a particularly stark loss in the year 2012 — but fortunately, it does not appear that there has been another doubling of the rate of mass loss since 2010, says Box. Not yet, anyway.

Nevertheless, the fact that Greenland has already contributed so much fresh water to the oceans, and that now its ice loss is speeding up, is sobering. The key question for the future of Greenland’s ice is how high temperatures will go and how long they will stay there. The world’s recent Paris goal of keeping warming well below 2 degrees Celsius (or even better, 1.5 degrees Celsius), if achieved, may just be enough to prevent a scenario in which a total melt occurs over time.“The ice sheets are doomed in plus 3 Celsius world,” says Box.

I thought no arctic sea ice, no GIS as the paleo climate people found out, at least no complete ice sheet, even Northeast Greenland started to loose ice recently.

Could be a bit like the sea ice were not expected to melt this century, everything is happening faster as expected, especially with the methane feedback, leaking subsea permafrost and the rest.Surface melt will go slow, until that tipping point when cracks reach way down and things start to slide, even East Antarctica has its weaknesses.I would argue that the GIS and the other NH ice caps are remnents of an ice age and we are abruptly entering a hothouse. As the NH has so much more landmass it is more sensitive to global warming, add the changing currents of the Northern Atlantic and the altered jet and polar vortex, an ideal mix for a rapid phase change, making Greenland Finally green instead the vast icy wilderness with a few patches of green on the edges like it is now.In the distant past you had vast forests that could moderate worldwide climate changes, a healthy ocean, sea life as well.I do not think the GIS can handle a 10 degree average temp.jump.I'd love to see pics from those cracks on Southwest Greenland, signs of an imminent collapse but then I am a doomer who loves giant waves that pose a danger to our coastal affairs, especially me being a lowlander

Natural climate changes in Earth's history have been accompanied by huge sea-level changes: After the last Ice Age, global sea levels rose by 120 meters. We still have enough ice on Earth to raise sea levels by a further over 60 meters. How stable are these huge ice masses in the face of global warming?

Stefan Rahmstorf obtained his PhD in oceanography at Victoria University of Wellington in 1990. He has worked as a scientist at the New Zealand Oceanographic Institute, at the Institute of Marine Science in Kiel and since 1996 at the Potsdam Institute for Climate Impact Research. His work focuses on the role of the oceans in climate change.

Fine interview with video's of Grace mission, GIS loosing mass and a model run of 5 millenia that would result after the tipping point of lower elevation by melt, increasing temp as a result and so on.We are loosing the GIS after 1 degree Global warming.Marine ice instability as well, certain for the WAIS.

The first photographs of a new and ominous crack in Greenland’s enormous Petermann Glacier were captured by a NASA airborne mission Friday.NASA’s Operation IceBridge, which has been flying over northwest Greenland for the past several days, took the photos after being provided coordinates by Stef Lhermitte, a professor at Delft University of Technology in the Netherlands, who had spotted the oddly located chasm by examining satellite images.

Ok, that were Petermann glacier, the floating terminus shelf, not the sheet of Greenland.

We know that Greenland's ice sheets are melting as the world gets warmer, but new research shows this process is speeding up, as a chain reaction of fast-draining lakes compound the problem of diminishing ice cover.These lakes, located on the surface of the ice, are caused by warmer temperatures. As they drain, they end up quickly transferring a lot of water and heat down to the base of the ice sheet. Faster flows lead to new fractures – which means other lakes can then drain at a more rapid rate.This chain reaction of water drainage is capable of temporarily speeding up ice flow by as much as 400 percent, according to an international team of scientists. Once large cracks in the ice start to appear, the stability of the entire ice sheet is put under greater threat.

"This ice sheet, which covers 1.7 million square kilometres [656,374 square miles], was relatively stable 25 years ago, but now loses one billion tonnes of ice every day," says one of the team, Poul Christoffersen from the University of Cambridge in the UK."This causes one millimetre [0.04 inches] of global sea level rise per year, a rate which is much faster than what was predicted only a few years ago."

Scientists already know plenty about these lakes and the effects they can have, but the new research suggests the damage they can do is more serious than was previously thought, because of the cascading effects happening under the ice.These effects put the ice under increasing pressure, leading to tensile shocks and fractures. Solid ice far away from the edge of the sheet gets exposed to water and heat that it wouldn't otherwise come into contact with.The lakes can exist for several weeks or months, but take just hours to drain. In this study, the researchers combined real-world observations spanning several years with a detailed 3D computer model to assess the potential impact of these lakes.

Lakes and meltwater streams on the Greenland ice sheet. (Timo Lieber)In some cases, the chain reaction effect could speed up the drainage of other lakes as far as 80 kilometres (49.7 miles) away, the research found. One scenario was noted where 124 lakes drained over the course of just five days.This network of "melt lakes" reaches as far as 135 kilometres (83.9 miles) inland, according to the study – a distance previously thought to be impossible. They also reach elevations as high as 2,000 metres (6,562 feet).

"Transfer of water and heat from surface to the bed can escalate extremely rapidly due to a chain reaction," says Christoffersen. "In one case we found all but one of 59 observed lakes drained in a single cascading event. Most of the melt lakes drain in this dynamic way."

The satellites are reporting a wealth of observations that are revealing new hidden facts about the ice sheets continuously. For instance, we have observations of the size of the Greenland ice sheet every month going back to 2002. You can look towards the bottom of the screen here to see the month and the year go forward. You can see that some areas of the ice sheet melt or lose ice in the summer. Other areas experience snowfall or gain ice back in the winter. This seasonal cycle, though, is eclipsed by an overall rate of mass loss that would have stunned a glaciologist 50 years ago. We never thought that an ice sheet could lose mass into the ocean this quickly. Since these measurements began in 2002, the ice sheet has lost so much ice that if that water were piled up on our smallest continent, it would drown Australia knee-deep. How is this possible? Well, under the ice lies the bedrock. We used radar to image the hills, valleys, mountains and depressions that the ice flows over. Hidden under the ice sheet are channels the size of the Grand Canyon that funnel ice and water off of Greenland and into the ocean.

Just six years ago, we had no idea this glacier aquifer existed. The aquifer formed when snow melts in the summer sun and trickles downward. It puddles up in huge pools. From there, the snow acts as an igloo, insulating this water from the cold and the wind above. So the water can stay hidden in the ice sheet in liquid form year after year. The question is, what happens next? Does the water stay there forever? It could. Or does it find a way out to reach the global ocean? One possible way for the water to reach the bedrock and from there the ocean is a crevasse, or a crack in the ice. When cracks fill with water, the weight of the water forces them deeper and deeper. This is how fracking works to extract natural gas from deep within the earth. Pressurized fluids fracture rocks. All it takes is a crack to get started.

Like the leaking subsea permafrost, a crack, a pathway is all it takes Well, we recently discovered that there are cracks available in the Greenland ice sheet near this glacier aquifer. You can fly over most of the Greenland ice sheet and see nothing, no cracks, no features on the surface, but as this helicopter flies towards the coast, the path that water would take on its quest to flow downhill, one crack appears, then another and another. Are these cracks filled with liquid water? And if so, how deep do they take that water? Can they take it to the bedrock and the ocean? To answer these questions, we need something beyond remote sensing data. We need numeric models.

Last edited by Whitefang on Sun 24 Mar 2019, 08:32:57, edited 2 times in total.

DescriptionPetermann Glacier is a large glacier located in North-West Greenland to the east of Nares Strait. It connects the Greenland ice sheet to the Arctic Ocean at 81°10' north latitude, near Hans Island. The glacier and its fjord are named after German cartographer August Heinrich Petermann. Wikipedia

That big flat Berg I posted a pic of above likely was a small remnant of a previous crack in the Peterman glacier.

A large chunk estimated to be 100 square miles (260 km2) calved off the glacier[6] in August, 2010.

Did you go all the way up the westcoast? Tricky with ice going south...

Oh, from the Ted talk of Kristin P. and interview of the Danish scientist, the Grace mission that covers the ice mass loss of Greenland between 2004 and 2014, total mass loss about 2500 Gton, 250 Gton a year on average.Interesting to see that last 5 years, we could be over 300 Gton a year already, another doubling.

It’s no news that Greenland is in serious trouble — but now, new research has helped quantify just how bad its problems are. A satellite study, published last week in the journal Geophysical Research Letters, suggests that the Greenland ice sheet lost a whopping 1 trillion tons of ice between the years 2011 and 2014 alone. And a big portion of it came from just five glaciers, about which scientists now have more cause to worry than ever. It’s the latest story in a long series of increasingly worrisome studies on ice loss in Greenland. Research already suggests that the ice sheet has lost at least 9 trillion tons of ice in the past century and that the rate of loss has increased over time. Climate scientists are keeping a close eye on the region because of its potentially huge contributions to future sea-level rise (around 20 feet if the whole thing were to melt) — not to mention the damage it’s already done. Ice loss from Greenland may have contributed as much as a full inch of sea-level rise in the last 100 years and up to 10 percent of all the sea-level rise that’s been documented since the 1990s. The new study takes a detailed look at ice loss in Greenland between 2011 and 2014 using measurements from the CryoSat-2, an environmental research satellite launched by the European Space Agency in 2010. It relied on a type of measurement known as altimetry — basically, measuring how the surface of Greenland’s altitude changed over time in response to ice gains or losses.

Data from NASA's GRACE satellites show that the land ice sheets in both Antarctica (upper chart) and Greenland (lower) have been losing mass since 2002. Both ice sheets have seen an acceleration of ice mass loss since 2009. (Source: GRACE satellite data)Please note that the most recent data are from June 2017, when the GRACE mission concluded science operations. Users can expect new data from GRACE’s successor mission, GRACE Follow-On, in the summer of 2019.​

Data on the GIS up to june 2017, grace 2 from next summer on. 286 Gton a year…...not above 300.So we have undersurface lakes that do not need any melt, just a way to get through to the ocean, like free methane that is under pressure and looking for a way to reach the atmosphere.

Daily melt extent mapping is suspended for the winter. Calibration of yearly melt detection requires analysis of the springtime snow conditions by a separate program. See our March 18, 2013 post for more discussion of melt calibration.Our new interactive chart supports a retrospective look at past Greenland melt seasons. This will remain active for our users.We will resume the daily image updates in April 2019.

As noted in the previous post, exceptional winter snow accumulation and heavy, summer snowfall, drove the net snow input mass to 130 billion tons above the 1981 to 2010 average. This was followed by a near-average melt and runoff period, resulting in a large net mass gain for the ice sheet in 2018 of 150 billion tons. This is the largest net gain from snowfall since 1996, and the highest snowfall since 1972. However, several major glaciers now flow significantly faster than in these earlier years. The net change in mass of the ice sheet overall, including this higher discharge of ice directly into the ocean, is not clear at this point but may be a smaller loss or even a small gain. This is similar to our assessment for 2017, and in sharp contrast to the conditions for the preceding decade.

Looks like the GIS has its ups and downs on mass loss, alike the female mood swings

The ice margin just reaches the sea, however, in a region of irregular topography in the area of Melville Bay southeast of Thule. Large outlet glaciers, which are restricted tongues of the ice sheet, move through bordering valleys around the periphery of Greenland to calve off into the ocean, producing the numerous icebergs that sometimes occur in North Atlantic shipping lanes. The best known of these outlet glaciers is Jakobshavn Glacier (Greenlandic: Sermeq Kujalleq), which, at its terminus, flows at speeds of 20 to 22 metres or 66 to 72 feet per day.

How fast the melt would eventually occur is a matter of discussion. According to the IPCC 2001 report,[2] such warming would, if kept from rising further after the 21st Century, result in 1 to 5 meter sea level rise over the next millennium due to Greenland ice sheet melting. Some scientists have cautioned that these rates of melting are overly optimistic as they assume a linear, rather than erratic, progression. James E. Hansen has argued that multiple positive feedbacks could lead to nonlinear ice sheet disintegration much faster than claimed by the IPCC. According to a 2007 paper, "we find no evidence of millennial lags between forcing and ice sheet response in paleoclimate data. An ice sheet response time of centuries seems probable, and we cannot rule out large changes on decadal time-scales once wide-scale surface melt is underway."[12]

The melt zone, where summer warmth turns snow and ice into slush and melt ponds of meltwater, has been expanding at an accelerating rate in recent years. When the meltwater seeps down through cracks in the sheet, it accelerates the melting and, in some areas, allows the ice to slide more easily over the bedrock below, speeding its movement to the sea. Besides contributing to global sea level rise, the process adds freshwater to the ocean, which may disturb ocean circulation and thus regional climate.[7] In July 2012, this melt zone extended to 97 percent of the ice cover.[14] Ice cores show that events such as this occur approximately every 150 years on average. The last time a melt this large happened was in 1889. This particular melt may be part of cyclical behavior; however, Lora Koenig, a Goddard glaciologist suggested that "...if we continue to observe melting events like this in upcoming years, it will be worrisome."[15][16][17] Global warming is increasing growth of algae on the ice sheet. This darkens the ice causing it to absorb more sunlight and potentially increasing the rate of melting.[18]

A study published in 2016, by researchers from the University of South Florida, Canada and the Netherlands, used GRACE satellite data to estimate freshwater flux from Greenland. They concluded that freshwater runoff is accelerating, and could eventually cause a disruption of AMOC in the future, which would affect Europe and North America.[29] A 2018 international study found that the fertilizing effect of meltwater around Greenland is highly sensitive to the glacier grounding line depth it is released at. Retreat of Greenland's large marine-terminating glaciers inland will diminish the fertilizing effect of meltwater- even with further large increases in freshwater discharge volume.[30] Recent ice loss events[edit]Between 2000 and 2001: Northern Greenland's Petermann glacier lost 85 square kilometres (33 sq mi) of floating ice.Between 2001 and 2005: Sermeq Kujalleq broke up, losing 93 square kilometres (36 sq mi) and raised awareness worldwide of glacial response to global climate change.[31]July 2008: Researchers monitoring daily satellite images discovered that a 28-square-kilometre (11 sq mi) piece of Petermann broke away.August 2010: A sheet of ice measuring 260 square kilometres (100 sq mi) broke off from the Petermann Glacier. Researchers from the Canadian Ice Service located the calving from NASA satellite images taken on August 5. The images showed that Petermann lost about one-quarter of its 70 km-long (43 mile) floating ice shelf.[32]July 2012: Another large ice sheet twice the area of Manhattan, about 120 square kilometres (46 sq mi), broke away from the Petermann glacier in northern Greenland.[33]In 2015, Jakobshavn Glacier calved an iceberg about 4,600 feet (1,400 m) thick with an area of about 5 square miles (13 km2).[6]Media[edit]

Two mechanisms have been utilized to explain the change in velocity of the Greenland Ice Sheets outlet glaciers. The first is the enhanced meltwater effect, which relies on additional surface melting, funneled through moulins reaching the glacier base and reducing the friction through a higher basal water pressure. (It should be noted that not all meltwater is retained in the ice sheet and some moulins drain into the ocean, with varying rapidity.) This idea was observed to be the cause of a brief seasonal acceleration of up to 20% on Sermeq Kujalleq in 1998 and 1999 at Swiss Camp.[34] (The acceleration lasted between two and three months and was less than 10% in 1996 and 1997 for example. They offered a conclusion that the "coupling between surface melting and ice-sheet flow provides a mechanism for rapid, large-scale, dynamic responses of ice sheets to climate warming". Examination of recent rapid supra-glacial lake drainage documented short term velocity changes due to such events, but they had little significance to the annual flow of the large outlet glaciers.[35] The second mechanism is a force imbalance at the calving front due to thinning causing a substantial non-linear response. In this case an imbalance of forces at the calving front propagates up-glacier. Thinning causes the glacier to be more buoyant, reducing frictional back forces, as the glacier becomes more afloat at the calving front. The reduced friction due to greater buoyancy allows for an increase in velocity. This is akin to letting off the emergency brake a bit. The reduced resistive force at the calving front is then propagated up-glacier via longitudinal extension because of the backforce reduction.[36][37] For ice streaming sections of large outlet glaciers (in Antarctica as well) there is always water at the base of the glacier that helps lubricate the flow. If the enhanced meltwater effect is the key, then since meltwater is a seasonal input, velocity would have a seasonal signal and all glaciers would experience this effect. If the force imbalance effect is the key, then the velocity will propagate up-glacier, there will be no seasonal cycle, and the acceleration will be focused on calving glaciers. Helheim Glacier, East Greenland had a stable terminus from the 1970s–2000. In 2001–2005 the glacier retreated 7 km (4.3 mi) and accelerated from 20 to 33 m or 70 to 110 ft/day, while thinning up to 130 meters (430 ft) in the terminus region. Kangerdlugssuaq Glacier, East Greenland had a stable terminus history from 1960 to 2002. The glacier velocity was 13 m or 43 ft/day in the 1990s. In 2004–2005 it accelerated to 36 m or 120 ft/day and thinned by up to 100 m (300 ft) in the lower reach of the glacier. On Sermeq Kujalleq the acceleration began at the calving front and spread up-glacier 20 km (12 mi) in 1997 and up to 55 km (34 mi) inland by 2003.[38] On Helheim the thinning and velocity propagated up-glacier from the calving front. In each case the major outlet glaciers accelerated by at least 50%, much larger than the impact noted due to summer meltwater increase. On each glacier the acceleration was not restricted to the summer, persisting through the winter when surface meltwater is absent. An examination of 32 outlet glaciers in southeast Greenland indicates that the acceleration is significant only for marine-terminating outlet glaciers—glaciers that calve into the ocean.[39] A 2008 study noted that the thinning of the ice sheet is most pronounced for marine-terminating outlet glaciers.[40] As a result of the above, all concluded that the only plausible sequence of events is that increased thinning of the terminus regions, of marine-terminating outlet glaciers, ungrounded the glacier tongues and subsequently allowed acceleration, retreat and further thinning.[39][41][42][43]

Analysis of gravity data from GRACE satellites indicates that the Greenland ice sheet lost approximately 2900 Gt (0.1% of its total mass) between March 2002 and September 2012. The mean mass loss rate for 2008–2012 was 367 Gt/year.[49] A paper on Greenland's temperature record shows that the warmest year on record was 1941 while the warmest decades were the 1930s and 1940s. The data used was from stations on the south and west coasts, most of which did not operate continuously the entire study period.[50] While Arctic temperatures have generally increased, there is some discussion concerning the temperatures over Greenland. First of all, Arctic temperatures are highly variable, making it difficult to discern clear trends at a local level. Also, until recently, an area in the North Atlantic including southern Greenland was one of the only areas in the World showing cooling rather than warming in recent decades,[51] but this cooling has now been replaced by strong warming in the period 1979–2005.[52]

Several factors determine the net rate of growth or decline. These are Accumulation and melting rates of snow in the central partsMelting of surface snow and ice which then flows into moulins, falls and flows to bedrock, lubricates the base of glaciers, and affects the speed of glacial motion. This flow is implicated in accelerating the speed of glaciers and thus the rate of glacial calving.Melting of ice along the sheet's margins (runoff) and basal hydrology,Iceberg calving into the sea from outlet glaciers also along the sheet's edgesExplanation of accelerated glacial coastward movement and iceberg calving fails to consider another causal factor: increased weight of the central highland ice sheet. As the central ice sheet thickens, which it has for at least seven decades, its greater weight causes more horizontal outward force at the bedrock. This in turn appears to have increased glacial calving at the coasts. Visual evidence for increased central highland ice sheet thickness exists in the numerous aircraft that have made forced landings on the icecap since the 1940s. They landed on the surface and later disappeared under the ice.[45] A notable example is the Lockheed P-38F Lightning World War II fighter plane Glacier Girl that was exhumed from 268 feet of ice in 1992 and restored to flying condition after being buried for over 50 years. It was recovered by members of the Greenland Expedition Society after years of searching and excavation, eventually transported to Kentucky and restored to flying condition.

A bit long but still interesting........367 Gton a year which would mean another doubling of massive loss

I had intended to sail to Greenland but got worn out by the time I got to Southern Labrador. Once I hit the Labrador Current it got coooold. There were lots of coastal bergs. I had a good clean weather window to run to Greenland, where it was warmer, but realized I’d have to come back through the cold Labrador Current. Not something I wanted to take on single handed.

Whitefang, consider this. At 300gt a year it will take 15,000 years for it all to melt. Double it to 600 a year and it will take 7000 years and double it again and it still takes 3500 years. Not rally going to be a problem for you and I. Now when ameba are growing in a petre dish they double in a certain amount of time fixed by their biology and food supply and once doubled because and only because there are now twice as many individuals they will double again in that same amount of time if they don't run out of food. The same is not true about the melting of a block of ice or a glacier. Having once doubled it's melting rate does not have to double again in the same amount of time or a shorter one. It is a mater of the surface area which doesn't change and the air temperature (and sea water temp for the edge in the water) and how much that changes. Now we started out with very little net melt as far as we know considering the quality of the historical data so starting from zero melt any melt is a large percent change but insignificant to the total. It is similar to the doubling of EV cars or wind mill numbers installed. A big increase year on year but still a tiny fraction of the total energy or auto mix. So calm down, the sky is not falling, and our great grand children will run out of oil and coal and live in a clean post fossil fuel world with reduced CO2 in the air and a Greenland still covered by two mile thick ice cap.

I’m personally not much worried about SLR, nor do I consider it in my future planning, and I don’t think it will effect my Great grandchildren much. I do think it will negatively effect NO, NYC, and other areas and we should now be planning to retreat from them, we should stop investing in areas that will be inundated within the foreseeable future.

But to then say our great grandchildren will run out of coal and live in a pure environment is a very long stretch indeed. As I recall the effects of CO2 in the atmosphere last for some very long time, centuries. So the CO2 we have today will mostly still be with us in 100 years, plus all the new accumulation.

And the projections for coal stores are that they could lower the plant for several centuries. So 100 years of BAU burning fossil fuels is a short estimate. Could be 200 or 300.

Anyway, best not to focus on any one bit of AGW, best to take a broad view.

I think we will reach a true peak in oil production sometime this decade 19-29 and will probably boost coal consumption in an effort to substitute it for oil but the total of all fossil fuels being burned will probably peak inside the next twenty-five years and then taper off quite rapidly both from people adopting cleaner alternatives and a leveling off or even a decline in world population. I don't know how fast the plant life on the planet can recapture the excess CO2 in the atmosphere but just a cessation of us dumping more in each year should help a lot and give the forests and phytoplankton a chance to catch up.

Greenland’s fastest retreating glacier is advancing and rebuilding. The meme of accelerating GIS melting is going to be needing a rewrite. Similar behaviour is showing up on glaciers in Iceland. Expect more of the same evidence of cooling with grand solar minimum approaching in the next couple years.

Jakobshavn Isbrae has been the single largest source of mass loss from the Greenland Ice Sheet over the last 20 years. During that time, it has been retreating, accelerating and thinning. Here we use airborne altimetry and satellite imagery to show that since 2016 Jakobshavn has been re-advancing, slowing and thickening. We link these changes to concurrent cooling of ocean waters in Disko Bay that spill over into Ilulissat Icefjord. Ocean temperatures in the bay’s upper 250 m have cooled to levels not seen since the mid 1980s.

According to researchers from the University of Iceland, ALL Icelandic glaciers are projected to expand this year, this would make it the first time the glaciers wouldn’t have shrunk year-on-year in a quarter of a century.The researchers were shocked by the discovery that all of Iceland’s glaciers, including Vatnajökull, Langjökull, Hofsjökull and Mýrdalsjökull, have expanded in the last twelve months, from autumn to autumn. With Mýrdalsjökull showing a really “significant addition of ice this year.”

While this is “good news” on a temporary basis, this is bad news on the long term because it tells scientists that ocean temperature is a bigger player in glacier retreats and advances than previously thought, said NASA climate scientist Josh Willis, a study co-author. Over the decades the water has been and will be warming from man-made climate change, he said, noting that about 90 percent of the heat trapped by greenhouse gases goes into the oceans.

“In the long run we’ll probably have to raise our predictions of sea level rise again,” Willis said.

While this is “good news” on a temporary basis, this is bad news on the long term because it tells scientists that ocean temperature is a bigger player in glacier retreats and advances than previously thought, said NASA climate scientist Josh Willis, a study co-author. Over the decades the water has been and will be warming from man-made climate change, he said, noting that about 90 percent of the heat trapped by greenhouse gases goes into the oceans.

“In the long run we’ll probably have to raise our predictions of sea level rise again,” Willis said.

It’s not good news or bad news, it’s knowledge and betters our understanding of natural phenomenon. Whether this glacier is melting or growing is meaniless to all of humanity other than to a few scientists who gain employment by studying it and making extrapolations of doom or no doom.

IPCC models of future climate trends contain a number of departures from patterns deduced from the paleoclimate evidence. With CO₂ levels reaching 411.8 ppm in January 2019 and CH₄ levels reaching 1.867 ppm in October 2018, for a greenhouse radiative forcing factor of CH₄=25 CO₂ equivalents, the total CO₂-equivalent of 457.5 ppm¹ approaches the stability limit of the Greenland ice sheet, estimated at a greenhouse gas forcing of approximately 500 ppm CO₂ although ephemeral ice may have existed as far back as the middle Eocene. As the concentration of greenhouse gases is rising and amplifying feedbacks from land, oceans and ice sheet melting increase, transient temperature reversals (stadials) accentuate temperature polarities between warming land masses and oceanic regions cooled by the flow of cold ice melt water from the ice sheets, leading to extreme weather events. The rise in Arctic temperatures, at a rate twice as fast as that of lower latitudes, weakens the polar boundary and results in undulation of the jet stream, allowing warm air masses to shift north across the boundary, further heating the polar region. The weakened boundary further allows cold air masses to breach the boundary shifting away from the Arctic. Combined with the flow of ice melt water from Greenland, these developments are leading to a cooling of sub-polar oceans and adjacent land. Similar growth of cold water pools occur along the fringes of Western Antarctica. The cold water pools cover deeper warmer salt water layers which melt the frontal glaciers. The slow-down of the AMOC is analogous to Pleistocene (2.6-0.01 Ma) and early Holocene stadial freeze events such as the Younger Dryas (12.9 – 11.7 kyr) and the 8.5 kyr Laurentide ice melt, where peak temperatures were followed closely by sharp cooling. Climate projections by Hansen et al. (2016) suggest a stadial event associated with significant sea level rise and involving sharp cooling of approximately -2°C, lasting several decades between the mid-21 st century and the mid-22nd century, a time dependent on the rate of Greenland and Antarctic ice melt. Accelerating ice melt and nonlinear sea level rise would reach multi-meters levels over a timescale of 50–150 years.

What the hell do you expect scientists to do if not collect data and then attempt to make predictions on it? If all they did was collect data and then sit on it that would be pretty useless.

I think this quote nicely summarizes the manor in which climate scientists should conduct themselves.

I consider science to be one of the most valuable inventions of human civilization, and I recognize how precious and vulnerable to corruption it is as one who believes in objective reality, the fallibility of human perception, and the need for objective methods of seeking truth.

I also recognize that public trust in science itself depends heavily upon trust in the objectivity of those who pursue it. We must walk a fine line between defending truth and trying to force it on other people, and I personally choose to take a cautious approach in walking that line.

We reconstruct the mass balance of the Greenland Ice Sheet using a comprehensive survey of thickness, surface elevation, velocity, and surface mass balance (SMB) of 260 glaciers from 1972 to 2018. We calculate mass discharge, D, into the ocean directly for 107 glaciers (85% of D) and indirectly for 110 glaciers (15%) using velocity-scaled reference fluxes. The decadal mass balance switched from a mass gain of +47 ± 21 Gt/y in 1972–1980 to a loss of 51 ± 17 Gt/y in 1980–1990. The mass loss increased from 41 ± 17 Gt/y in 1990–2000, to 187 ± 17 Gt/y in 2000–2010, to 286 ± 20 Gt/y in 2010–2018, or sixfold since the 1980s, or 80 ± 6 Gt/y per decade, on average.

The acceleration in mass loss switched from positive in 2000–2010 to negative in 2010–2018 due to a series of cold summers, which illustrates the difficulty of extrapolating short records into longer-term trends.

Cumulated since 1972, the largest contributions to global sea level rise are from northwest (4.4 ± 0.2 mm), southeast (3.0 ± 0.3 mm), and central west (2.0 ± 0.2 mm) Greenland, with a total 13.7 ± 1.1 mm for the ice sheet. The mass loss is controlled at 66 ± 8% by glacier dynamics (9.1 mm) and 34 ± 8% by SMB (4.6 mm). Even in years of high SMB, enhanced glacier discharge has remained sufficiently high above equilibrium to maintain an annual mass loss every year since 1998.